title: The cocoon sign: a potential sonographic pitfall in the diagnosis of twin - twin transfusion syndrome.
mesh_terms: D003951:Diagnostic Errors; D005260:Female; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal / Q000592:standards*